Cutter profile helping in stability and steerability

ABSTRACT

An improved drill bit comprises a bit body, a plurality of blades disposed on the bit body, a first plurality of cutting elements disposed on the blades, such that the first plurality of cutting elements define a first cutter profile, and a second plurality of cutting elements disposed on the blades, such that the second plurality of cutting elements define a second cutter profile offset from the first cutter profile. The first plurality of cutting elements may, or may not, be greater in number than the second plurality of cutting elements. The cutting elements of the first plurality may, or may not, be greater in size than the cutting elements of the second plurality. The second cutter profile may be offset inwardly or outwardly from the first cutter profile. The second cutter profile may run along a cone section, a nose section, and/or a shoulder section of the bit.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The inventions disclosed and taught herein relate generally to drillbits, such as for drilling into earth formations; and more specificallyrelate to cutter profiles for such drill bits that improve performanceespecially in the areas of stability and steerability.

2. Description of the Related Art

U.S. Pat. No. 4,440,247 teaches a “blade-type rotary drill bit havingradially divergent cutting blades arranged in two arrays and equippedwith cutting blanks having upset cutting surfaces formed of an abrasivematerial such as diamond or the like. The blades in one array cut to thecenter of the bit to provide a conically shaped core volume and theblades of the second array terminate short of the axis of the bit todefine a somewhat larger core volume. The bit is equipped with dischargeports and baffles whereby drilling fluid issuing from the dischargeports moves downwardly and then inwardly to the center of the bit. Thecutting blanks located on the second array of blades cut in a common setof tracks which are at least partially different from and compliment thetracks cut by the cutting blanks on the blade of the first array.”

U.S. Pat. No. 4,593,777 teaches a “drill bit comprises a bit body havingan operating end face. A plurality of self-sharpening cutters aremounted in the bit body and extend through the operating end face. Thecutters have cutting faces adapted to engage an earth formation and cutthe earth formation to a desired three-dimensional profile. The cuttingfaces define surfaces have back rake angles which decrease with distancefrom the profile. The individual cutting faces may be inwardly concavein a plane parallel to the intended direction of motion of the cutter inuse. Each of the cutting members has a stud portion disposed in arespective recess in the bit body and defining the inner end of thecutting member, the cutting face being generally adjacent the outer endand having an outer cutting edge. The centerline of the stud portion isrearwardly inclined, from the outer end to the inner end, with respectto the direction of movement in use, taken at the midpoint of thecutting edge, at a first angle from 80.degree. to 30.degree. inclusive.The cutting face is oriented such that the tangent to the cutting faceat the midpoint of the cutting edge and in the center plane of thecutting member is disposed at a second angle, for 18.degree. to75.degree. inclusive, with respect to the centerline of the studportion.”

U.S. Pat. No. 4,932,484 teaches a “whirl resistant drill bit isdisclosed for use in rotary drilling. The drill bit includes a generallycylindrical bit body with a plurality of cutting elements extending outfrom a lower end surface. The cutter elements are grouped in sets suchthat a first set of cutters are disposed at substantially an equalradius from a center of the bit body to create a groove in the materialbeing drilled. A second set of cutters is connected to the lower endsurface with each cutter therein in overlapping radial relationship witheach other and extending a maximum distance from the lower end surfaceless than that of the first set of cutters. At least one cutter of thesecond set is in overlapping radial relationship with at least one ofthe cutters within the first set of cutters. This cutter arrangementcauses the drill bit to cut grooves within the formation material thattends to prevent destructive bit whirl. Further, adjustments can be madeto vary the back rake angle and side rake angle to prevent bit whirl.”

U.S. Pat. No. 5,033,560 teaches an “earth boring bit having a bodyprovided with a shank having a tubular bore and a head along theopposite end of said body having flow passages communicating with thebore, the head having face portions including a center end face portion,a nose portion, a shoulder portion, and a gage portion along the maximumdiameter of the bit, and cutting elements mounted over said faceportions having cutting faces oriented in the direction of rotation ofthe drill bit, the areas of the cutting faces of the cutting elementsranging from a maximum at the center face portion to a minimum at thegage portion of the bit. The cutters may be individually mounted,mounted in groups, arranged in random patterns, and arranged in avariety of other patterns, including radial longitudinal rowscircumferentially spaced around the bit face.”

U.S. Pat. No. 5,238,075 teaches a “fixed cutter drill bit includes aplurality of angularly spaced radial wings each with a row of cuttingelements mounted thereon and protruding from the bit for drillingthrough formation material. On a first of the wings, a first row of thecutting elements has alternately larger and smaller area cutting facesat spaced selected radial positions relative to the center of the bit.Similarly, a second row of cutting elements is mounted on a second ofthe wings at substantially the same radial positions but with the radialpositions of the larger and smaller cutting faces reversed over those onthe first wing. A third wing includes a third row of cutting elementswith cutting faces of intermediate area located at each of the selectedradial positions. The combination of different sizes of cutting elementsat each radial position defines a set having a profile with theintermediate and smaller cutting elements located entirely within thelarger cutting element. The profiles of the larger cutting elements ofadjacent sets overlap each other without substantial overlapping of theprofiles of any of the other cutting elements.”

U.S. Pat. No. 5,549,171 teaches a “fixed cutter drill bit includes setsof cutter elements mounted on the bit face. Each set includes at leasttwo cutters mounted on different blades at generally the same radialposition with reset to the bit axis but having differing degrees ofbackrake. The cutter elements of a set may be mounted having theircutting faces out-of-profile, such that certain elements in the set areexposed to the formation material to a greater extent than other cutterelements in the same set. The cutter elements in a set may have cuttingfaces and profiles that are identical, or they may vary in size or shapeor both. The bit exhibits increased stability and provides substantialimprovement in ROP without requiting excessive WOB.”

U.S. Pat. No. 5,551,522 teaches a “fixed cutter drill bit includes acutting structure having radially-spaced sets of cutter elements. Thecutter element sets preferably overlap in rotated profile and include atleast one low profile cutter element and at least two high profileelements. The low profile element is mounted so as to have a relativelylow exposure height. The high profile elements are mounted at exposureheights that are greater than the exposure height of the low profileelement, and are radially spaced from the low profile element on the bitface. The high profile elements may be mounted at the same radialposition but at differing exposure heights, or may be mounted at thesame exposure heights but at different radial positions relative to thebit axis. Providing this arrangement of low and high profile cutterelements tends to increase the bit's ability to resist vibration andprovides an aggressive cutting structure, even after significant wearhas occurred.”

U.S. Pat. No. 5,607,025 teaches a “fixed cutter drill bit includescutter elements mounted in sets on the bit face. A cutter element setincludes at least three cutters with cutting faces having at least twodifferent curvatures. The cutter elements of the set are mounted onvarious blades of the bit such that, in rotated profile, the cuttingprofile of a larger and a smaller cutter element overlap, and such thatthe smaller cutter element is flanked by larger sized cutters. The bitexhibits increased stability, before and after wear has occurred. Thelarge cutters provide for efficient shearing while the smaller cuttersmay provide prefracturing in certain formations.”

U.S. Pat. No. 5,582,261 teaches a “fixed cutter drill bit includes setsof cutter elements mounted on the bit face, each set including at leasttwo cutters that are mounted at generally the same radial position withrespect to the bit axis. The cutter elements of a set are positioned ondifferent blades of the bit and are mounted having their cutting facesare out-of-profile, such that certain elements in the set are exposed tothe formation material to a greater extent than other cutter elements inthe same set. The cutter elements in a set may have equal diameters ormay vary in size. The bit exhibits increased stability or vibrationresistance, and drills initially as a ‘light-set’ bit and later as a‘heavy-set’ bit.”

U.S. Pat. No. 7,000,715 teaches a “superabrasive cutter-equipped rotarydrag bit especially suitable for directional drilling in subterraneanformations is provided. The bit may employ PDC cutters in an engineeredcutter placement profile exhibiting optimal aggressiveness in relationto where the cutters are positioned along the profile of the bitextending from a cone region laterally, or radially, outward toward agage region therefore. The engineered cutter placement profile mayinclude cutters exhibiting differing degrees of aggressivenesspositioned in order to maximize rate-of-penetration and minimizetorque-on-bit while maintaining side cutting capability andsteerability.”

The inventions disclosed and taught herein are directed to drill bitswith improved cutter profiles for enhancing performance and specificallystability and steerability.

BRIEF SUMMARY OF THE INVENTION

Applicants have created an improved drill bit, such as for drilling intoan earth formation. The drill bit preferably comprises a bit body, aplurality of blades disposed on the bit body, a first plurality ofcutting elements disposed on the blades, such that the first pluralityof cutting elements define a first cutter profile, and a secondplurality of cutting elements disposed on the blades, such that thesecond plurality of cutting elements define a second cutter profileoffset from the first cutter profile. The first plurality of cuttingelements may, or may not, be greater in number than the second pluralityof cutting elements. The cutting elements of the first plurality may, ormay not, be greater in size than the cutting elements of the secondplurality. The second cutter profile may be offset inwardly or outwardlyfrom the first cutter profile. The second cutter profile may run along acone section, a nose section, and/or a shoulder section of the drillbit.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an exemplary drill bitincorporating cutting elements and embodying certain aspects of thepresent inventions;

FIG. 2 is an enlarged perspective view of an exemplary cutting elementembodying certain aspects of the present inventions;

FIG. 3 is a partial elevation view of a blade of a drill bit accordingto certain aspects of the present inventions;

FIG. 4 is an elevation view of a cutter profile of a drill bit accordingto certain aspects of the present inventions;

FIG. 5 is a elevation view of multiple cutter profiles of a drill bitaccording to certain aspects of the present inventions;

FIG. 6 is another elevation view of multiple cutter profiles of a drillbit according to certain aspects of the present inventions; and

FIG. 7 is another elevation view of multiple cutter profiles of a drillbit according to certain aspects of the present inventions.

DETAILED DESCRIPTION

The Figures described above and the written description of specificstructures and functions below are not presented to limit the scope ofwhat Applicants have invented or the scope of the appended claims.Rather, the Figures and written description are provided to teach anyperson skilled in the art to make and use the inventions for whichpatent protection is sought. Those skilled in the art will appreciatethat not all features of a commercial embodiment of the inventions aredescribed or shown for the sake of clarity and understanding. Persons ofskill in this art will also appreciate that the development of an actualcommercial embodiment incorporating aspects of the present inventionswill require numerous implementation-specific decisions to achieve thedeveloper's ultimate goal for the commercial embodiment. Suchimplementation-specific decisions may include, and likely are notlimited to, compliance with system-related, business-related,government-related and other constraints, which may vary by specificimplementation, location and from time to time. While a developer'sefforts might be complex and time-consuming in an absolute sense, suchefforts would be, nevertheless, a routine undertaking for those of skillin this art having benefit of this disclosure. It must be understoodthat the inventions disclosed and taught herein are susceptible tonumerous and various modifications and alternative forms. Lastly, theuse of a singular term, such as, but not limited to, “a,” is notintended as limiting of the number of items. Also, the use of relationalterms, such as, but not limited to, “top,” “bottom,” “left,” “right,”“upper,” “lower,” “down,” “up,” “side,” and the like are used in thewritten description for clarity in specific reference to the Figures andare not intended to limit the scope of the invention or the appendedclaims.

Applicants have created an improved drill bit, such as for drilling intoan earth formation. The drill bit preferably comprises a bit body, aplurality of blades disposed on the bit body, a first plurality ofcutting elements disposed on the blades, such that the first pluralityof cutting elements define a first cutter profile, and a secondplurality of cutting elements disposed on the blades, such that thesecond plurality of cutting elements define a second cutter profileoffset from the first cutter profile. The first plurality of cuttingelements may, or may not, be greater in number than the second pluralityof cutting elements. The cutting elements of the first plurality may, ormay not, be greater in size than the cutting elements of the secondplurality. The second cutter profile may be offset inwardly or outwardlyfrom the first cutter profile. The second cutter profile may run along acone section, a nose section, and/or a shoulder section of the drillbit.

FIG. 1 is an illustration of a drill bit 10 that includes a bit body 12having a conventional pin end 14 to provide a threaded connection to aconventional jointed tubular drill string rotationally andlongitudinally driven by a drilling rig. Alternatively, the drill bit 10may be connected in a manner known within the art to a bottomholeassembly which, in turn, is connected to a tubular drill string or to anessentially continuous coil of tubing. Such bottomhole assemblies mayinclude a downhole motor to rotate the drill bit 10 in addition to, orin lieu of, being rotated by a rotary table or top drive located at thesurface or on an offshore platform (not shown within the drawings).Furthermore, the conventional pin end 14 may optionally be replaced withvarious alternative connection structures known within the art. Thus,the drill bit 10 may readily be adapted to a wide variety of mechanismsand structures used for drilling subterranean formations.

The drill bit 10, and select components thereof, are preferably similarto those disclosed in U.S. Pat. No. 7,048,081, which is incorporatedherein by specific reference. In any case, the drill bit 10 preferablyincludes a plurality of blades 16 each having a forward facing surface,or face 18. The drill bit 10 may have anywhere from two to sixteenblades 16. While in one preferred embodiment, the face 18 issubstantially flat, it may be concave and/or convex.

The drill bit 10 also preferably includes a row of cutters, or cuttingelements, 20 secured to the blades 16. The drill bit 10 also preferablyincludes a plurality of nozzles 22 to distribute drilling fluid to cooland lubricate the drill bit 10 and remove cuttings. As customary in theart, gage 24 is the maximum diameter which the drill bit 10 is to haveabout its periphery. The gage 24 will thus determine the minimumdiameter of the resulting bore hole that the drill bit 10 will producewhen placed into service. The gage of a small drill bit may be as smallas a few centimeters and the gage of an extremely large drill bit mayapproach a meter, or more. Between each blade 16, the drill bit 10preferably has fluid slots, or passages, 26 into with the drilling fluidis fed by the nozzles 22.

An exemplary cutting element 20 of the present invention, as shown inFIG. 2, includes a super-abrasive cutting table 28 of circular,rectangular or other polygon, oval, truncated circular, triangular, orother suitable cross-section. The super-abrasive table 28, exhibiting acircular cross-section and an overall cylindrical configuration, orshape, is suitable for a wide variety of drill bits and drillingapplications. The super-abrasive table 28 of the cutting element 20 ispreferably formed with a conglomerated super-abrasive material, such asa polycrystalline diamond compact (PDC), with an exposed cutting face30. The cutting face 30 will typically have a top 30A and a side 30Bwith the peripheral junction thereof serving as the cutting region ofthe cutting face 30 and more precisely a cutting edge 30C of the cuttingface 30, which is usually the first portion of the cutting face 30 tocontact and thus initially “cut” the formation as the drill bit 10retaining the cutting element 20 progressively drills a bore hole. Thecutting edge 30C may be a relatively sharp approximately ninety-degreeedge, or may be beveled or rounded. The super-abrasive table 28 willalso typically have a primary underside, or attachment, interface joinedduring the sintering of the diamond, or super-abrasive, layer formingthe super-abrasive table 28 to a supporting substrate 32 typicallyformed of a hard and relatively tough material such as a cementedtungsten carbide or other carbide. The substrate 32 may be preformed ina desired shape such that a volume of particulate diamond material maybe formed into a polycrystalline cutting, or super-abrasive, table 28thereon and simultaneously strongly bonded to the substrate 32 duringhigh pressure high temperature (HPHT) sintering techniques practicedwithin the art. Alternatively, the substrate 32 may be formed of steel,or other strong material with an abrasion resistance less than that oftungsten carbide and/or the earth formation being drilled. In stillother embodiments, the substrate 32 may comprise a relatively thintungsten carbide layer backed by a steel body.

In any case, the substrate 32 may be cylindrical, conical, tapered,and/or rectangular in over-all shape, as well as, circular, rectangularor other polygon, oval, truncated circular, and/or triangular, incross-section. A unitary cutting element 20 will thus be provided thatmay then be secured to the drill bit 10 by brazing or other techniquesknown within the art, such as gluing, press fitting, and/or using a studmounting technique.

In accordance with the present invention, the super-abrasive table 28preferably comprises a heterogeneous conglomerate type of PDC layer ordiamond matrix in which at least two different nominal sizes and wearcharacteristics of super-abrasive particles, such as diamonds ofdiffering grains, or sizes, are included to ultimately develop a rough,or rough cut, cutting face 30, particularly with respect to the cuttingface side 30B and most particularly with respect to the cutting edge30C. In one embodiment, larger diamonds may range upwards ofapproximately 600 μm, with a preferred range of approximately 100 μm toapproximately 600 μm, and smaller diamonds, or super-abrasive particles,may preferably range from about 15 μm to about 100 μm. In anotherembodiment, larger diamonds may range upwards of approximately 500 μm,with a preferred range of approximately 100 μm to approximately 250 μm,and smaller diamonds, or super-abrasive particles, may preferably rangefrom about 15 μm to about 40 μm.

The specific grit size of larger diamonds, the specific grit size ofsmaller diamonds, the thickness of the cutting face 30 of thesuper-abrasive table 28, the amount and type of sintering agent, as wellas the respective large and small diamond volume fractions, may beadjusted to optimize the cutter 20 for cutting particular formationsexhibiting particular hardness and particular abrasivenesscharacteristics. The relative, desirable particle size relationship oflarger diamonds and smaller diamonds may be characterized as a tradeoffbetween strength and cutter aggressiveness. On the one hand, thedesirability of the super-abrasive table 28 holding on to the largerparticles during drilling would dictate a relatively smaller differencein average particle size between the smaller and larger diamonds. On theother hand, the desirability of providing a rough cutting surface woulddictate a relatively larger difference in average particle size betweenthe smaller and larger diamonds. Furthermore, the immediately precedingfactors may be adjusted to optimize the cutter 20 for the averagerotational speed at which the cutting element 20 will engage theformation as well as for the magnitude of normal force and torque towhich each cutter 20 will be subjected while in service as a result ofthe rotational speeds and the amount of weight, or longitudinal force,likely to be placed on the drill bit 10 during drilling.

While PDC cutters, such as those discussed above, are used in apreferred embodiment, other cutters may be used alternatively and/oradditionally. For example, cutters made of thermally stablepolycrystalline (TSP) diamond, in triangular, pin, and/or circularconfiguration, cubic boron nitride (CBN), and/or other superabrasivematerials may be used. In some embodiments, even simple carbide cuttersmay be used.

The blades 16 of modern drill bits often have three or more sectionsthat serve related and overlapping functions. Specifically, referring toFIG. 3, each blade 16 preferably has a cone section, nose section, ashoulder section, and a gage section. The cone section of each blade ispreferably a substantially linear section extending from near acenter-line of the drill bit 10 outward. Because the cone section isnearest the center-line of the drill bit 10, the cone section does notexperience as much, or as fast, movement relative to the earthformation. The slope and length of the cone section commonly influencesstability of the bit 10.

The nose represents the lowest point on a drill bit. Therefore, the nosecutter is typically the leading most cutter. The nose section is roughlydefined by a nose radius. A larger nose radius provides more area toplace cutters in the nose section. The nose section begins where thecone section ends, where the curvature of the blade 16 begins, andextends to the shoulder section. More specifically, the nose sectionextends where the blade profile tangentially matches a circle formed bythe nose radius. The nose section experiences much more, and more rapid,relative movement than does the cone section. Additionally, the nosesection typically takes more weight than the other sections. As such,the nose section experiences much more wear than does the cone section.The nose section is also a more significant contributor to rate ofpenetration and drilling efficiency than the cone section.

The shoulder section begins where the blade profile departs from thenose radius and continues outwardly on each blade 16 to a point where aslope of the blade is essentially completely vertical, at the gagesection. The shoulder section experiences much more, and more rapid,relative movement than does the cone section. Additionally, the shouldersection typically takes the brunt of abuse from dynamic dysfunction,such as bit whirl. As such, the shoulder section experiences much morewear than does the cone section. The shoulder section is also a moresignificant contributor to rate of penetration and drilling efficiencythan the cone section.

The gage section begins where the shoulder section ends. Morespecifically, the gage section begins where the slope of the blade ispredominantly vertical. The gage section continues outwardly to an outerperimeter or the gage 24 of the drill bit 10. The gage sectionexperiences the most, and most rapid, relative movement with respect tothe earth formation. However, at least partially because of the high,substantially vertical, slope of the blade 16 in the gage section, thegage section does not typically experience as much wear as does theshoulder section and/or the nose section. The gage section does,however, typically experience more wear than the cone section.

Referring also to FIG. 4, the row of cutters 20 are preferably spacedalong a curved outer edge of the face 18 of each blade 16, forming afirst, or primary, curved cutter, or cutting, profile, or layout, 34.The cutter profile 34, as shown, is a composite of the cutting elements20 on each blade 16, as the bit 10 rotates through the earth formation.In other words, the cutter profile 34 comprises each of the cuttingelements 20 super-imposed as if each cutting elements 20 were rotatedinto a single plane of a blade 16 extending from bit body 12. In manycases, the profile 34 generally follows the shape of the blades 16.

According to certain aspects of the present invention, however, theremay be more than one cutter profile 34. For example, referring also toFIG. 5, the bit 10 may have a first, or primary, cutter profile 34, anda second, or secondary, cutter profile 36 offset from the first cutterprofile 34. As shown in FIG. 5, FIG. 6, and FIG. 7, the second cutterprofile 36 may be offset inwardly or outwardly from the first cutterprofile 34. The second cutter profile 36 may be offset from the firstcutter profile 34 between 0.020 inches and 0.2 inches, or more. In onepreferred embodiment, the second cutter profile 36 is offset from thefirst cutter profile 34 approximately 0.15 inches. The second cutterprofile 36 may be offset from the first cutter profile 34 by somepercentage of the cutter diameter. For example, the second cutterprofile 36 may be offset from the first cutter profile 34 by betweentwenty-five and seventy-five percent of the diameter of the cuttingelements 20, of the first profile 34, the second profile 36, or anaverage thereof. In one embodiment, the second cutter profile 36 isoffset from the first cutter profile 34 by approximately 50% of thediameter of the cutting elements 20, of the first profile 34.

The second cutter profile 36 may be located along the cone, nose, and/orshoulder sections. More specifically, the secondary cutter profile 36may span more than one adjacent section, such as the cone and nosesections, and/or may span two or more non-adjacent sections, such as thecone and shoulder sections, with the first cutter profile 34 beinglocated along the remaining sections.

The second cutter profile 36 preferably comprises a plurality of thecutting elements 20. The second cutter profile 36 may, or may not,comprise all of the cutting elements 20 in the affected section, orsections. For example, the second cutter profile 36 may comprise betweenfive and one hundred percent of the cutting elements 20 in the affectedsection or sections. In one embodiment, the second cutter profile 36comprises approximately all of the cutters 20 in the cone section. Inanother embodiment, the second cutter profile 36 comprises approximately75% of the cutters 20 in the nose section. In another embodiment, thesecond cutter profile 36 comprises approximately 50% of the cutters 20in the shoulder section.

In any case, as also shown in FIG. 5, FIG. 6, and FIG. 7, the secondcutter profile 36 may comprise fewer cutting elements 20 than the firstcutter profile 34. Alternatively, the second cutter profile 36 maycomprise roughly the same number, or more, cutting elements 20 than thefirst cutter profile 34. In one embodiment, the first cutter profile 34comprises approximately forty cutting elements, while the second cutterprofile comprises approximately ten cutting elements. The second cutterprofile 36 may comprise a percentage of the cutting elements 20, such asten, fifteen, or twenty percent. Alternatively, the second cutterprofile 36 may comprise a fraction of the cutting elements 20, such asone-quarter, one-third, or one-half.

In one embodiment, the cutting elements 20 in each profile 34, 36 areoriented similarly, other than the offset. In other embodiments, thecutting elements 20 in the second profile 36 utilize a different backrake and/or side rake. For example, in one embodiment, the cuttingelements 20 in the second profile 36 utilize more back rake than thecutting elements 20 in the first profile 34.

Other and further embodiments utilizing one or more aspects of theinventions described above can be devised without departing from thespirit of Applicant's invention. For example, the cutting elements 20 ineach profile may be the identical. Alternatively, the cutting elements20 may be differently sized, shaped, and/or constructed. Additionally,or alternatively, the drill bit 10 may include three or more cutterprofiles, with each being inwardly or outwardly and located in any ofthe blade sections. Further, the various methods and embodiments of thepresent invention can be included in combination with each other toproduce variations of the disclosed methods and embodiments. Discussionof singular elements can include plural elements and vice-versa.

The inventions have been described in the context of preferred and otherembodiments and not every embodiment of the invention has beendescribed. Obvious modifications and alterations to the describedembodiments are available to those of ordinary skill in the art. Thedisclosed and undisclosed embodiments are not intended to limit orrestrict the scope or applicability of the invention conceived of by theApplicants, but rather, in conformity with the patent laws, Applicantsintend to fully protect all such modifications and improvements thatcome within the scope or range of equivalent of the following claims.

1. A drill bit, such as for drilling into an earth formation, the drillbit comprising: a bit body; a plurality of blades disposed on the bitbody; a first plurality of cutting elements disposed on the blades, suchthat the first plurality of cutting elements define a first cutterprofile; and a second plurality of cutting elements disposed on theblades, such that the second plurality of cutting elements define asecond cutter profile offset from the first cutter profile, wherein eachprofile is exclusive for at least a portion of each blade.
 2. The drillbit as set forth in claim 1, wherein the first plurality of cuttingelements are greater in number than the second plurality of cuttingelements.
 3. The drill bit as set forth in claim 1, wherein the cuttingelements of the first plurality are greater in size than the cuttingelements of the second plurality.
 4. The drill bit as set forth in claim1, wherein the second cutter profile is offset inwardly from the firstcutter profile.
 5. The drill bit as set forth in claim 1, wherein thesecond cutter profile is offset outwardly from the first cutter profile.6. The drill bit as set forth in claim 1, wherein the second cutterprofile runs along a cone section.
 7. The drill bit as set forth inclaim 6, wherein the first cutter profile runs along a gage section, ashoulder section, and a nose section, but not the cone section.
 8. Thedrill bit as set forth in claim 1, wherein the second cutter profileruns along a nose section.
 9. The drill bit as set forth in claim 8,wherein the first cutter profile runs along a gage section, a shouldersection, and a cone section, but not the nose section.
 10. A drill bit,such as for drilling into an earth formation, the drill bit comprising:a bit body; a plurality of blades disposed on the bit body; a firstplurality of cutting elements disposed on the blades, such that thefirst plurality of cutting elements define a first cutter profile; and asecond plurality of cutting elements disposed on the blades, such thatthe second plurality of cutting elements are fewer in number than thefirst plurality of cutting elements and define a second cutter profileoffset from the first cutter profile, wherein the first cutter profileruns along a gage section and a shoulder section, and wherein the secondcutter profile exclusively runs along at least a portion of at least oneof a nose section and a cone section.
 11. The drill bit as set forth inclaim 10, wherein the second cutter profile is offset inwardly from thefirst cutter profile.
 12. The drill bit as set forth in claim 10,wherein the second cutter profile is offset outwardly from the firstcutter profile.
 13. The drill bit as set forth in claim 1, wherein thesecond cutter profile is offset from the first cutter profile by atleast 0.15 inches.
 14. The drill bit as set forth in claim 1, whereinthe second cutter profile is offset from the first cutter profilebetween twenty-five and seventy-five percent of an average diameter ofthe first plurality of cutting elements.
 15. The drill bit as set forthin claim 1, wherein the second cutter profile is offset from the firstcutter profile between twenty-five and seventy-five percent of anaverage diameter of the second plurality of cutting elements.
 16. Thedrill bit as set forth in claim 1, wherein the second cutter profile isoffset from the first cutter profile between twenty-five andseventy-five percent of an average diameter of the cutting elements. 17.The drill bit as set forth in claim 10, wherein the second cutterprofile is offset from the first cutter profile by at least 0.15 inches.18. The drill bit as set forth in claim 10, wherein the second cutterprofile is offset from the first cutter profile between twenty-five andseventy-five percent of an average diameter of the first plurality ofcutting elements.
 19. The drill bit as set forth in claim 10, whereinthe second cutter profile is offset from the first cutter profilebetween twenty-five and seventy-five percent of an average diameter ofthe second plurality of cutting elements.
 20. The drill bit as set forthin claim 10, wherein the second cutter profile is offset from the firstcutter profile between twenty-five and seventy-five percent of anaverage diameter of the cutting elements.
 21. A drill bit, such as fordrilling into an earth formation, the drill bit comprising: a bit body;a plurality of blades disposed on the bit body; a first plurality ofcutting elements disposed on the blades, such that the first pluralityof cutting elements define a first cutter profile; and a secondplurality of cutting elements disposed on the blades, such that thesecond plurality of cutting elements define a second cutter profileoffset from the first cutter profile, wherein the second cutter profileis offset from the first cutter profile by at least 0.15 inches.
 22. Adrill bit, such as for drilling into an earth formation, the drill bitcomprising: a bit body; a plurality of blades disposed on the bit body;a first plurality of cutting elements disposed on the blades, such thatthe first plurality of cutting elements define a first cutter profile;and a second plurality of cutting elements disposed on the blades, suchthat the second plurality of cutting elements define a second cutterprofile offset from the first cutter profile, wherein the second cutterprofile is offset from the first cutter profile between twenty-five andseventy-five percent of an average diameter of the first plurality ofcutting elements.
 23. A drill bit, such as for drilling into an earthformation, the drill bit comprising: a bit body; a plurality of bladesdisposed on the bit body; a first plurality of cutting elements disposedon the blades, such that the first plurality of cutting elements definea first cutter profile; and a second plurality of cutting elementsdisposed on the blades, such that the second plurality of cuttingelements define a second cutter profile offset from the first cutterprofile, wherein the second cutter profile is offset from the firstcutter profile between twenty-five and seventy-five percent of anaverage diameter of the second plurality of cutting elements.
 24. Adrill bit, such as for drilling into an earth formation, the drill bitcomprising: a bit body; a plurality of blades disposed on the bit body;a first plurality of cutting elements disposed on the blades, such thatthe first plurality of cutting elements define a first cutter profile;and a second plurality of cutting elements disposed on the blades, suchthat the second plurality of cutting elements define a second cutterprofile offset from the first cutter profile, wherein the second cutterprofile is offset from the first cutter profile between twenty-five andseventy-five percent of an average diameter of the cutting elements.